The invention discloses an automatic adjustment type multistage measuring weir. The automatic adjustment type multistage measuring weir comprises a weir plate, the weir plate is sequentially provided with 2-3 weir crests from low to high, and the center lines of the weir crests overlap; a transmission device is arranged on the top of the weir plate and comprises a transmission rod parallel with the top side of the weir plate, and a transmission motor is arranged at one end of the transmission rod; weir gates vertically sliding between the weir crests are arranged on the outer surface of the weir plate, and the number of the weir gates is smaller than the number of the weir crests by one; a pair of guide grooves are formed in the weir plate in symmetry along the center line and in parallel, are formed in the two sides of the weir gates and are parallel with the weir gates; 1-2 pairs of transmission belts are arranged on the weir plate in symmetry along the center line and in parallel and are arranged on the outer sides of the guide grooves. The automatic adjustment type multistage measuring weir can effectively adapt to the condition that the amplitude of the downstream water level is large, the flow regime of the measuring weir can be guaranteed, the phenomenon that observation cannot be carried out because of submerged flow can be prevented, and the phenomenon that the seepage condition of hydraulic structures is influenced because weir crests are arranged too high and the upstream water level of the measuring weir is too high can be avoided.